Im sure some of you have seen
http://typerain.deviantart.com/ stuff, but im almost 100% sure it hasnt been posted here. Mostly because he hasnt drawn anything growth related. Except this
http://typerain.deviantart.com/gallery/#/d2adbce its someone elses picture yes, but he modified it to show growth and did a pretty good job of it. That and the rest of his gallery has some cute muscle girls which is worth checking out even if there is no process.